1. Technical Field
The present disclosure relates to a technology for manufacturing an image sensor using a backside illumination photodiode, and more particularly, to an image sensor using a backside illumination photodiode and a method for manufacturing the same, in which a process may be simplified and a misalignment margin may be secured when bonding two wafers.
2. Related Art
FIG. 1 illustrates the structure of a conventional image sensor which is manufactured through a 3D CIS (CMOS image sensor) manufacturing process.
Referring to FIG. 1, an image sensor 100 includes a top wafer 100T which has a plurality of top metal layers 110T, a plurality of top vias 120T and a plurality of top bonding pads 130T, and a bottom wafer 100B which has a plurality of bottom metal layers 110B, a plurality of bottom vias 120B and a plurality of bottom bonding pads 130B.
The plurality of top metal layers 110T which are formed in the top wafer 100T are respectively electrically connected to the top bonding pads 130T through the top vias 120T with a corresponding number.
Similarly, the plurality of bottom metal layers 110B which are formed in the bottom wafer 100B are respectively electrically connected to the bottom bonding pads 130B through the bottom vias 120B with a corresponding number.
The top wafer 100T and the bottom wafer 100B are electrically connected by the top bonding pads 130T and the bottom bonding pads 130B which are formed to face each other.
In this way, the conventional image sensor 100 has a structure in which the top wafer 100T and the bottom wafer 100B are electrically connected with each other by the top bonding pads 130T which are formed to correspond to the number of the top metal layers 110T in the top wafer 100T and the bottom bonding pads 130B which are formed to correspond to the number of the bottom metal layers 110B in the bottom wafer 100B.
However, the image sensor 100 structured in this way may be encountered with a problem in that the characteristics of pixels are likely to deteriorate due to the parasitic capacitance induced in the pluralities of bonding pads 130T and 130B. Also, another problem may be caused in that a process margin is likely to become insufficient due to a misalignment.